Steam boiler



l. HARTER STEAM BOILER Sept. 23, 1930.

Original Filed Oct. 29. 1921 7 SheetsSheef INVENTOR 94a M BY l ATTORN EYs l, HARTER Sept. 23', 1930.

STEAM BOILER AOriginal Filed Oct. 29, 1921 '7 Sheets-Sheet OO OO OO OO OO OO o .ooooooooo ooooooooooo ooooooooooo o oom/000000 O O O O O O O O OO OO OO OO INVENTOR ATTORNEYS l. l-IARTER STEAM BOILER Sept. 23, 1930.

original Filed ook. 29, 1921 7l sheets-sheet INVENToR. ya@ Maz,

I '/2 A TTORNE YS.

sept. 23, 1930. l. HARTER 1,776,505

l STEAM BOILER Original VFiled Got. 29. 1921 7 Sheets-Sheet 4 GGO OQO @@Qbg@ O O O o u f GT OQO OOOQnC-)G I O OO C@ 0 O O @Q 0 [E o o @OOGOWQQOQ O O' o 0 OOG @O O- i-OOG O0@ :EL-'O O o 0G90@ G CD. e@ c@ w@ w w m m w w E@ m w @w w m m m @w `INPE/WOR.

A A TTORNEYS.

sept. 23, 1930. l. HARTER r 1,776,505

STEAM 'BOILER I original Filed oct. `29. '1921 7 sheets-sheet 5 INVENTOR.

l. HARTER STEAM BOILER septfzs, 1930.

Original Filed Oct?) 29, 1921 7 Sheets-Sheet 6 I INVENTOR. .9d-n.44. M1451,

BY 4%.4 f Lee ATTORNEYS.

l. HARTER sept.' 23, 1930.

STE'AM BOILER- Original Filed Oct. 29. 1921 7 Sheets-Sheet INVENTOR.

ATToRNEYs.

` tert-thas,

.Viso

i Patented seti. ,23.1930 f l invention boilers, particularly 'of the ,typelin which upper and 2 vlowerfhori'zontal vdrums are connected by waenc'ento y,the accompanying drawings, in which -Figl Ashows a` side elevation,fwith some for .the

boi'lersettingbrolen-away', oran illustrative t fao form .of boiler embodying my invention ,Fig

,v :f2.'i's a verticalsectiononthe line ,2-2f0f Fig.,

; Fig;r3 isa plan viewofFig.- .1, with some of .the parts broken away?? Figil 'isa developai rangement shown in-FigfhFig. 5l is a more 'or'flessf' diagrammaticrepresentation of some nofi the tubes showingth'e relation ofthe rows Y, side elevatiompartly in section, of stillan-y other embodiment" ofrnyv invention; Fig. 7 is f Y a-plan'viewof 'Figi -fwith somev of the parts -fbr'ok'enaway or removedrfor a better under- ,.Fig Sais a cross-section 'showing the stagi Y Y Igeredfarrangement of,l the tubes inthe form :of boilershown in Figs). 6,f7 and 8; FigsflQ, 5.11 andl2 are' venlarged sections respectively ,Y l 1.13f7is-f'an enlargement lof' a portion i of Y 1Fi'g.. 9,;Fig. Mis amore or less diagrammatic showing oitthe tube f arrangement of- Fig. '6

` lo and representsa section takenparallel'lto a drow. of tubes through'a portion ofthe lower Y 'l f drum; Fig. 1,5.,isan enlarged section'of a por- (tion.,of/a-drumtaken parallel to a row `of stub'esgFig. Vlois,arsection at"rightanglesto theaxisofthe drum; FigL-lf isa view of part' of Figfl looking from th'e'left of that iigure;Fig.v 18 is a 'side vview of a portion of Fig.

i if 15; 19 isan enlarged section of the lower 'drumf'of the arrangement shown infF ig. 6;.

v;Fig.j20r.is"aside'elevation, also enlarged, of

, :thegsar'ne drum and'someofthe tubes ;Fig. L isja sectionfon line 21-21 of Fig.y 20, and Fig.

L 22 is aplan view of'Fig. 20.

in the 4several views.

andin which'the ho'tigases o'w in a 511,5fgenerallyihorizontal 'directionr 1 Vlijly,invention willbeunder'stoodfby refer'- Sidewalls 14,715 provide afluefrom `ili'g fromthe lower drum411`up'rtoward'th'e V'upperfdrum110, fwith la' sufficient space between that* drumj and the top of 'the'baie'to `18 lextends' downward from the upper drain ,510,'and another rbaiile 19 extends'up 'fromthe rlowier'f drumrv ll`. 'f f The rear: off the settirrgf is Referring now Ito the arrangement shown which drums are horizontal anl one above the 0ther witlr1the upper 'dru'l'n il() projecting beyond the. end of the 'lower drum 11, l: Rows of inclined Iwater tubes 12 "connect: these sdru'msin a manner to be described more spe'- ciicallyf hereinafter, and beneaththef row of tubes at the left'of 'Figi l is' located" a? furnace .chamber 13 having any sutablemeans for bu-rnin'gany'desired'kind of fuelg y the furnace/chamber 13'f to conduct the "gases therefrom toward the right of "il, such o gase s ultimately .passing out the gasoutlet Within the flue formed by these side walls are arranged-'the tubes 12 infrows extending across"the'ue, 'such arrangement 'being best f Vshown inFig; 2.k i' Preferably', theseftubes are vvdiyidedin groupsbyfbaille's, the bafilelfll?, fwh'ieh VAisthe one fnearestfthe furnace chamber '13, being '.located, in:l the lillustrati've form, behind two rows of the tubes 12 and extend,

provide 'agas passage. Similarly, a baille closed by the rear wall'20p" f f Sonle ofthe rows of tubesarespaced apart, as 'best kshown in Fig;` 1, lto provide a"superheater 21j toV they inlet header of'fwh'ich' the Vsteam from the drum'l is'conducted by the S fpipe 22'4andfrom-.wliich the steam is taken 4through the outletpipeQB. j Itjwillbefseenthat in thel form of boiler .justdescribed, vthe entire space lbetween the r`front` and' rearmost rows; of tubes isfille'd awith rows o''tub'es which are' parallelthe ,greater portion off their length 'and through K v`which thegasespass bylowin'g substantially f l Like reference characters refer to like parts parallel with` :theL greater portion ofea'h ,The'bend 4at either endris determined by lcer- A over the baiiiey 17, under thebaHle 18 and over the baille 19 to the gas eXit 16.,` Byfhav -ing the tubesinclined over the furnaoe'chamber 13, such tubes form a vroof for rthe furnace, and at the same time, by making the gas passage at= the upper ',end of Vthe battle 17,

o a combustion fach'afmber is `providedrin Y,which .the vgases will be mixed and burnedbefore.y

entering ,the tubes-j: The two rows @if tubes `radially.y :This is 1 aocom'pl-ishedby an ar-r rangement of' tubeswhich will appear as shown infFig. Qnwhenviewed from :the end Y 'ofthe' boiler. o,

^ v In order that the tubes may thedruins Y lradiallya'ndithat at th Sametime, the 'greater fporltions f otv Ysuch tubes; may be inclined as Shownfin FigfsxLiI have provided: amethod of bendingandl inserting they tubes, so'that ea-ch. tubeilw-illhave' `only two bends.` Thief v however, v will involvea peculiar arrange,` fment of theholes'linfthe drum, suoli holes ,falling-in curves which are illustrated infFig.`

.r4-,the relation betweenfthe'` upper and lower .ends of thetubes beingalso shown in'Fig. 1.

ftain fixed conditions in each tube. As willbe ,.seen by? an;inspectionfjofA Figs.' 1 and ,2,2 in y Y I each-tubeftherezfwill beja"straightportionV which'i's vparallel toa thev straightY portions of all vof the iother tubes,v and this straight p0rtion will have'a relation .gto the aX'es of the y two drums infaccordance with thevpo'sition of the,l tube relative to;l the vertical vaxis of '.thegboiler. Beginning at the vtubes nearest .qthisvertioalraxia it will beobviousthat the end of-thetube whichenters the drum must lie-finy av nearly vertical `-line,r'adial tothe drum,fand that,-thereforethe curve between the tube endandthe inclined straight -porvtionfof-the tjubejmay bean arc-of ay circle to which vthese .two straight portions., will be tangent, the bends ati-"theopposite Vends of thetubesbeing ,on opposite sides of thelplaneV .o fthe Y rowV in l' whichffthe tube;` is located.. .K yjSinin'larlfy,v the yneXt-tube must enter vthe drum lon aff-radial line,but=this radial linewill, be .at an angleg to the vertical, @11d thev f curve i which connects this radialfline with the center line. of `the, vrincl inedstraigl'lt portion of; [the tubemay also .be 'anr arc ofa circle-Lto which the center lines oflthe inclined straight poras aroundrthe drum'. In 'other words', the intersections of the normals of the'V tube'holes dTheholes lfor the tubesl in the drums should be spacedalongfthe axisoffthe drum aswell inthe drum will bespaced along the'aXis of thedrunil "In suchan arrangement, no. two

Il'oft-,the` tubesffrom the- 'center to the outside Vf yIrl-the arrangen'ientshown in fFig,y 6,-theVV ytubes are arrangedin-parallelrows and each*V tubefis bent inafsingle plane at eachend and, n in ,forderte kpermitsucha single bend. toenter the'drum normal lto, .the surfacetbereoif',;' p constructionVv offwhiclifw-ill `bebest vunderstood, 105.1 gby an inspection oFigst-l()1to`13,inclusive.

plane of thebend atthe other" end.

AIn the arrangement shown iniFigs. land 2, it may-be desirable order; to; provideJ minimum spacej Acondltionsffand reasonable] Y o rangement of tubes, when applied toy-agonvstruction in which teach tube'gis :to haveflonly two bends, f will produceva dru1n.sheet, .the f Y* developmentofwhichwill bey such as' Vis illus-V ligament-s between the `tube holes in theV drum sheet t0. have, the inner tubes staggered While theijfioutri tubes are ,ralallellifSch.alla# vv'rangement is shown in -Figkyin -whioh 'the n l"y four outery tubes at either side inl eaohrow are'arranged onel behind the oth"er,whilefthe remaining tubesy are staggeredf-Sruoh anar-Y1l ly so .trated inVFig'.4,the centerlinegfor- 'each row' l 'being as indicated for oneofthe y'rowsby Hthe lineV.-g--V in F igl- 74.1) j [il :In Figs; 6 to 8, inclusive, I havefillustrated" .a formof boiler in .whichthe'tubesrmayfbe bent inrone plane only andjyet'bef inclined 90.

forwardly and will-'galsoenter the drumnon substantially the* samer as lthoseishown in Fig. Y

repeated ldetail description thereof willzbe unnecessary; zThe formfofeboiler shown inf Y Fig; 6 is provi'dedywithanunderfeed Stoker Y 'Y hand-tired; grates shown instead, of .the

provide the druml with steps lor bumps-the v1,-andtare correspondingly numbered, anda Y f The angle which vthe axis-ofthe endV of a vgiven tube Y.will lmake L with 1 the vcylindrical f vsurface of the drum is ',irst determined, `and then'the'portion ofthe shell-into whichthe Y Y- endH of that tube is to befenter'edfis 'shaped by i Suitable dies,` 'so thatthe portionffthrough Wh-,'clithetube hole is inadewill lie-at'riglitjanglesf,tofgthisfaXis ft will bev lobvious that asinoe` each tubefend makesraif diierent langle `With V,the `cylindrical surfacethanv that: made `by its neighbor-lin" therow, V:the "angle which vthe 'plane offthisrfaceV will? make with theff' L Cylindrical 'drum' sur-face will bediierentfor ff reach of the tubesina Vrowfbginningat the ,A y'center and extendingtothe sid`e.` 'ln 'Figs' Y v H10s-t0 12' are shown enlargedfsections*of, th'e` steps 122, 132,''and 142101"` three rvadjacent '.ztub'esll, 131 and4 141 'in given frdw, kvandin Fig; 13 a plan lview of thesefsteps is shownii In this plan` view, for-salie'faclearnessythe steps arel shown ias'. i'fth'eflfa'ces :and sides welljas'acrossit. y.

In Fig. 14 is shown-.a

shown inV Figs: toil2, l inclusive. With Jthe staggered'` tube arrangement l as shown at the leftVr of Fig; 9, the ydevelopment of thedrium sheet Will be as, showninV iFig. ,9, withv the tube. holes forming curves yaround the `drum but'spaced Valong theflength lof the-drum as i sectionofa thedrumtalen paralleljto the tuberowk and Vm` showing the center lines of.thetubes1ofa rowv l and the curves at theends of eachof them. 1

'ffln Figs. 15 to 18,'inclusive, areshown sec-y 'tionsor side views of the drumfsheet as it will befbumped or lstepped .to yrecei've'soine of the e tubes,.the hole 121'being formed yinthe, step 122, the hole 131in the step 1.321and the hole fllllin the step 142,.theseuholes receiving the I ends of tubes 12, -13 and .14 indicated in Fig. f Brand therelation of these holes tothe others inthe same :row being also shown onthe drum IsheetdevelopmentinFigii9.

l gIn g.i22,a,plan Aviewof a portion of the lowerdrium 11,*withf somelolithe tubes lof a c row enteringxthe'same, is vshown whichwill further. illustrate the character'of thefsteps whichfare formed.

p, #The boilerV which. I lillustrated in various embodiments is eilicient `:and atfthe same ti1ne, economical rtovconstruct. By hav- `ingthe tubes inclined over thefurnace chamber, the radiant kheatv is absorbedl and atthe ysaine time, theediiliculties arising, `from4 ythe maintenance `of refractory r roofs- 4and arches are avoided. While,-for1;some purposes, .the

l tallyato` the; gas outlet, Iiind that, bypro-l Y pact/and eiiicient arrangement.

heatenis Iused, then-.afspace for iti-may be readily providedby omitting certain of the y rows oftubes at a point where .itis desired gases mightbe carried straightbackhorizonf .Viding` baliies so' as to compel they gases to flow Vup Aand down along thema'in portions of the tubes-asf the gasesflow horizontally; there willbe more"` efficient passage.v 'of `the heaty lron'ithegases tothe tubes'.` 'By arranging; all

of the tubes in' parallel rows, itgwill be oby vious; that all tubes'in likers'ituations'will be duplicates of each other. Thatis to say, all

.oftheV ,outermost tubesffor instance, in each rowk on one side will befalikeexce'pt where the .rows are staggered,.jin which case,the outermost tubes in each :alternate row willbe duplicates. Moreover, byplacing'all ofv the tubes inparallel rows, all ofthe boiler space may be iilled with tubes so as togifve a comasuperto kplace the super-heater, and where high i l superheat is'desired, such'spacefmay Vbe pro-` vided inthe first pass of the boiler, so that the V-superheater tubes willi be 'contacted by the hot gases after these gases have passed over av'fewfwater tubes only. Moreover, the upper andlower drumsfwwillbesimilar so far, as

Y' the.k arrangement of the tu'be holesitherein `are concerned,which is animportant considerakt1oi 11n=,the cost of' manufacture.

/Vhile thearrangements shownin Figs. -6, 7 andlSinvolve the forming' ofi` steps in the drum` Sheet, a great 'advantage isl derived therefrom f in the fact, that i the .tubes in this arrangementaresimple in design, and, more-'.- over,have the fewest possible` number `.of formsofgtubes fortheboiler, because each tubeat la given distance from tne vertical axis of the boilerwillbe the same as :the tube at the same distancefrom this vertical axis but outhe oppositesidethereof. f`

yunderstod that l include in ythat term any drumin which thepart enteredby the tubes is a part of a cylinder. It will also be understood that, while I have shown the upper and lowerA drums as of the saine length, the upper drum -may be extended, ifjdesired, until the end of the upperdrurn farthest from the furnace is over thecorresponding end ofv the lowerfdrum. Such an arrangement ywould give a vertical rear wall instead of the in elined rear wall which Ihave illustrated, and

will alsogive added steam'and water space,

so thatfthe steam could be taken fromy apoint in thev drum beneath which there are no water tubes.- f

Iclaimz-fA f; p-; 1. In a water-tube boiler, an upper and a lowercylindrical drum, with 'their axes horizontal and parallel, a furnace,a flue' arranged to conductthe hotfgases` fromthe furnacev between andlongitudinally cfcthe drums, a plurality ofvwater tubes [in the path of the gases and; connecting. ythe upper and. lowerA drums, thetubes being arranged in rows extending acrossthefiiuefwithi the greater .portion oft Ieach ofthe tubes in" each row in a plane perpendicular tothe plane of the axesf the drums and inclined toward tliefurnace "end ofthe flue, the distance betweenthe outer4 tubesk in each row 'being greater Athan-the diameter of one of said drums, the'y axisjof each end ofcach tube being'normal to that portion of the shell of the drum which the end enters and each tube having no more than two bends.

2. In a Water-tube boiler, an upper and a lower cylindrical drum, with their' axes horizontal kand parallel, av furnace,raflue yarranged to conduct the hotz gases `from the `furnace between and longitudinally offthc drums, a f plurality of rwater tubes in the path of the gases and connecting the upper malto that portionof'the shell of the drum;

l fio" y lower cylindrical'idr-urn,1A with their 'axesrv no more than two bends*k i v i y 3. In a water-tubefboiler,aniupper and a whichv Ithe endA enters'and each tube having horizontal and parallel, a furnace, a flue arranged tok conduct the hotgases-froin the Vfurnace between' and .longitudinallyv of `the drunns,- a plurality ofwater `tubesy inthe Vpath of the gasesfandconnecting the upper and lowerfdrums, thegreater portion of:

each tube'being inclined to the horizontal' in a; direction parallel tothe plane of the-axes of the drums, such greater portion of some of said ltubes beingbutside the projected area of at least one yof said drums, and each tube'being bent ina single plane, the portion of theshellf'ofl the drum which the end o f atube; enterscoinprising a step normal torr the axisof the end of the tube.

*4kg In a water-tubef-boiler, an 'upperandl a lower cylindrical drum, with their vaxes horizontal andparallel, a furnace, a flue arranged to conduct-the hot` gases from the furnace -betweeniandl longitudinally of the drums, a vplurality' of water tubes in the pathofthe gases and connecting the upper and lowe'rdrunis,. the .greater portion ofv each tube being inclined tothe horizontal'in V a` direction parallel to theplane of the axes the"bendsv being ina single plane,--the- 'por- Vof the drums, such greater portion of Asome of said tubes being outside the' projected area ofat least'oneof said drums, and each tube havingjno more` than two bends {and i ktion 'of the shell ofthe drum which theend of la'tube enters comprising a' step normal to the axis-of the end of thetube. y l` Y i 7 5. In a water-tube boilerfanupper and a Y lower cylindrical" drum, with their axes Y row ina plane `perpendicular to the plane,

beingrgreatervthan the diameter of one ofv Y' horizontal'and parallel, 'awfu'r1`1'acpe,V alfl'ue ar.

ranged toy conductyfthe hot gasesfvfrorn the i furnace kbetween and longitudinally fof the `ldl ru1ns,a plurality of water tubes intl'iepath" of the .gases and connectingtheA upperY and lower dru1ns,f"the tubes being Yarranged in Y 7 rows extending across the flue, .with the greater .portion l.of eachy of thegtubes'inreaeh ofthe axes ofthe drums and inclined` toward theffurnaoefend ofthe'flue, the distance 'between theouter tubesin -each row lsaiddruins, the tubes being bent betweeny the ends andthe inclined portion vand all ofthe bends ineach tube being in a single plane,`

theportion of the shell enteredby the ends 'Y 'La7-6,505

ofthe tubes having; Step-S ,of the ends ofthe tub'e` normal yto the' axes Y' 16,111 a watentube boiler, kan upper and a lower cylindrical drum,"` with `their axes Y horizontal and parallelfa furnace, ai `flue arranged to conduct the :hot f gases frorn, the'.V Y

furnace between andlongitudinally ofthe drums, a plurality of :water tubesinl the Y path" of-:Vthe gases andconnectingV the upperand' lower-drums, .the 'tubesibeing arran'gedl in rows extendingfacross the'ilue, with the greater yportion ofeach ofthe tubes in each row fin f a plane perpendicular tolthev plane ofthe vraxes ofthe drums andl 'inclined 'towardv the "furnace end vfof the fflue,'the dis#V Y' "tance 'between theV outer tubes in each row being greater than the; diameter of.; one offy sa-id drunis, the planes of the seize'ral rows beingp'aralleLthe tubes being bent-f'between i theends 'andthe inclined portions and all of the bends inea'ch tubebeingjinalsingle plane, the vportion of the shellenteredfbythey l ends yof the tubes having;stepsrnorrnahto f the axes of-the ends of the-tubes.- iVV Q7.' In a watertube boiler vannpper:and .af v lower cylindrical drunn'withtheir aXes'horizontal and parallel, a furnace,a flue arrangedl toconduct the hot gases fromthe furnace b'e-V Y i tween and' longitudinally 'of Athey drums', af'

plurality vofv water-tubes in the "pathi of the gases andconnecti'ngv the Vupper and lower drums, the tubes beingarranged in rows' eX* i tending across the flue, with thegreater portion ofy eachfof'the tubes ineach row inya fr ico] plane-'perpendicular to -theaplaneof the axes of the .drums land inclined. "toward",thelfur-y nace end :of the ivue,1rtl1edistancefbetween .the outer-tubes lin each row'being greater 1 thany the diametery of. roneof said dru'rns, the

axis of each endv of eachtube being normal to thatportion of theshell ofthe drum which the endenters and each tube having no incre than. two bends, and the pointsof'intersection of the axes of theen'dsfof the tubes of a row with the axes of the drum being spaced apart along the'druin aXis. i l8.In a water tube boiler, an upper and a kll() lower cylindrical druni,wijth their aXeshorie zontal and parallel, a furnace, a flue-"arranged i to-conductf'thehot gases -froin the furnace 'befplurality. of water tubes 'in 'the path of thel `tween and longitudinally* of the dri'i1n,fa

gases `and connectingpthe upper and lower e dru1ns,`the tubes-beingy arranged lin rows eX- tending-across theiiue, withthe-greater porplane perpendicular'to theplane of the axes I y of the druins and inclinedt'owardthe'furnace end of the flue, the distance between the outer tubes in e'ach'rowy being greater than the di'- anieter ofone o-f said Vdrums,tli( aXisof each and the points ofv-intersecti'oniofthe axesffof e end of each tubejbeingv normalto that lportion f of the shell, ofthe druniwhich 'the end enters I andeach tube having no more than two'bends, A

iso Y fao ' ytheendsfof the tubes of ay yrow with the axis Vof tliekdrum being spaced apart along the drum axis, such intersections loccurring alongsaid axis in the order of the'lcorresponding tubes from the outermost to the V.middle :of the row.

9. In a V'water-tube boiler, an'upperand a lower cylindricaldrum, with their axes horil* vrzontal and parallel, a furnace, a flue arranged `1o to conduct the hot gases from the furnace between and Vlongitudinally, of.L the drums, a

plurality of watertubes in the path of the Y ,drums, the greater portion of each tube being 15 4vinclined to the horizontal ina direction parf alleltoffthe'plane of the axes of the drums,

gases and connecting the'upper and lower i* suchgreater portion of some of said tubes being'V outside the projected area of at least one of said drums, and each tube being bent in av single plane, the portion of the shell j ofthe drum which the endv of a tube enters l*comprising a step normal to the axis of the vend of thet-ube and the external face of each such step being partiallybelow and partially vabove thev normal external surface of the 10. In a water tube'boiler, yan upper `anda lower cylindrical drum, with theirv axes hori- Zonta-l andpparallel, furnace,.-a flue arranged "to conduct thev hot gasesjfrom the furnace bef tween and longitudinally of the drums, va

` 7: plurality'of water tubes in the path of the gases and connecting the4 upper and lower drums,"the tubes being arranged in rows ex,-v

tending across the flue, with the greater portion ofeach of the tubes vin each row in a plane A' v'perpendicular to the 'plane of the axes of the drums and inclinedl toward the furnace end of' the flue, the Vaxis of each end of each tube beling normal to that portion of the shell of the drum which the end enters and each tube having no more than two bends, and the `points of L o intersection of the axes of the ends of theV f tubes of a row with the axis of the drum being spaced apart along the drum axis. v

11. vIn ay water tube boiler, an upper and a lower cylindrical drum, with their axes hori-k zontal and parallel, a furnace, aflue arranged,

y Y to conduct the hot gases from the furnace between and longitudinally of the drums, a plurality ofvwater tubes in the path of the gases andconnecting theupper and lower'drums,

.the tubes beingV arranged in rows extending' vacross the flue, with the greater portion of eachy of the tubes in each row 1n a'plane perpendicular to the plane ofthe axes of thev drums and inclined toward the furnace end of the flue, the axis ofi each end of 'each tube being normal to that portion of the shell of the drum which the end enters and each tube havspaced yapart along the drum axis, such intersections occurring along said axis in the order of thecorresponding tubes from the outermost to the middle'of the row.

l2.V In a water tube boiler, an upper and a lowerv cylindrical drum, with their axes hori- -zontal and parallel, afurnace, a flue arrangedr pendicular to the plane of the axes'of the t drums and inclined toward thefurnace end of the flue, the axis* of each end of each tube being normal to thatportion vof the shell of the drum which'the endenters and each tube having no more than two bends, and the ends of each tube being disposed substantially radially with respect to said drums. v

' 18. In a. water tube boiler, an upper and a lower cylindrical drum, with their axes horizontal and parallel, a furnace, a flue arranged f to conduct the hotgases from the furnace be tween and longitudinally of the drums, a plu-A rality of water tubes in the path of the gases and connecting the upper and lower drums, 't

the tubes being arranged in rows extending across the flue, with the greater portion of each of the tubes in each rowfin a planey perpendicular tothe plane of the axes of the drums and 'inclined toward the furnace end of the flue, the axis of each end of each tube being normalto that portion of the shell of the drum which the end enters and each tube having no more than two bends, the ends of each tube being disposed substantially radially'with respect to said drums, and being tending across the flue and havingtheir ends curved where they enter the drums, the center lines of said tubes which come in a given row, including the curved ends, falling in a plane perpendicular to the plane of the axes of the drums and inclined toward the furnace end of the flue., 4 y A Y ISAAC HARTER.

llO 

